The present invention relates to a navigation apparatus for outputting such audio information, and more particularly, to a navigation apparatus which selectively and preferentially outputs data which is truly necessary for a driver when there are a plurality of information to offer.
Along with recent tendency to process computer-related data in multimedia, multimedia has also rapidly found its way to be utilized in automobiles. Types of information handled in automobiles are, for instance, navigation information, VICS (Vehicle Information Control System) information, audio/visual information, radio, information from on-vehicle telephone, information from teletext broadcasting, information received from vehicle systems and the like.
A most serious problem in processing information from multimedia is simultaneous occurrence of an enormous amount of data. More specifically, a driver in an automobile receives a large amount of information e.g. information from VICS, information from multiplexed audio broadcasting and the like, from places where the driver does not take any part in. The obvious characteristic of the multimedia in automobiles is in that, in a case where a driver receives image data by a multimedia system, if the driver is not interested in the image, the driver simply needs to look away from a screen showing that image, so that the driver is not disturbed while driving the automobile.
However, in a case where the driver receives audio information where useful information and useless information are mixed, the driver must concentrate on the audio information to distinguish which information is useful. In addition, it is also difficult for a driver to ignore the information provided audibly. Especially, if unnecessary information is audibly provided while the driver is in an urgent situation, such information provided audibly may affect driver's performance.
Particularly with respect to regulating audio information output, for instance, Japanese Patent Application Laid-Open No. 1-142994, No. 5-203458 and No. 5-332778 disclose controlling of mainly the volume at the time of outputting audio information. However, when volume is controlled, a driver is required to concentrate even harder on the contents of the information because low volume is difficult to hear.
Furthermore, according to Japanese Patent Application Laid-Open No. 2-114117, a driver is able to set in advance a plurality of points where the driver desires to receive audio navigation, so that unnecessary audio guidance can be eliminated.
Moreover, according to Japanese Patent Application Laid-Open No. 4-1898, the length of guidance provided as audio information is controlled in accordance with vehicle speed, to synchronize outputting of the guidance information with passage of neighborhood of a destination point, whereby making it possible for a driver to associate what is seen with the contents of the guidance.
In addition, according to Japanese Patent Application Laid-Open No. 5-118866, a degree of driver's familiarity with respect to each road is determined by accumulating the number of times of driving the road, and in accordance with the degree of familiarity, audio information offering is controlled to be turned on/off. Since a driver does not need to audibly receive information on a familiar road, such unnecessary audio information is not provided.
Furthermore, according to a navigation apparatus disclosed in Japanese Patent Application Laid-Open No. 6-68385, two types of audio information, i.e., the first type of audio information outputted upon request of a driver and the second type of audio information provided automatically, are set. When the first type of audio information is to be outputted while the second type of audio information is being outputted, the second type of audio information is provided instead of the first type of audio information, or vice versa.
In the case of the aforementioned Japanese Patent Application Laid-Open No. 2-114117, if a large amount of multimedia data occur at the point where a driver desires audio navigation, all the information is provided to the driver and unnecessary information cannot be eliminated.
Even if the length of guidance provided as audio information is controlled in accordance with vehicle speed as disclosed in the aforementioned Japanese Patent Application Laid-Open No. 4-1898, in a case where a large amount of information occur simultaneously, a driver may receive information regarding the destination after the driver has already passed the destination.
Moreover, in the case of Japanese Patent Application Laid-Open No. 5-118866, if a large amount of plural audio information occur simultaneously while a driver is driving on an unfamiliar road, the driver may receive truly necessary information after receiving unnecessary information.
In other words, all the above-described conventional techniques are not capable of handling a case where there are plural information occurred simultaneously to be provided to a driver. Since these conventional techniques did not expect the arrival of the multimedia era in automobiles, drivers have to bear with useful and useless information mixed together.
Still further, in the navigation apparatus according to the aforementioned Japanese Patent Application Laid-Open No. 8-254437, either one of the two types of audio information (the aforementioned first type and second type of audio information) is always outputted whenever there is information to be provided. Thus, when both types of audio information occur, one of the types of audio information is outputted which may be useless to a driver at the time of output.